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If a vcpu has issued a HLT instruction with interrupts disabled then it sleeps

Browse source 
forever in vm_handle_hlt().

This is usually not an issue as long as one of the other vcpus properly resets
or powers off the virtual machine. However, if the bhyve(8) process is killed
with a signal the halted vcpu cannot be woken up because it's sleep cannot be
interrupted.

Fix this by waking up periodically and returning from vm_handle_hlt() if
TDF_ASTPENDING is set.

Reported by:	Leon Dang
Sponsored by:	Nahanni Systems
This commit is contained in:
Neel Natu 2014-07-26 02:53:51 +00:00
parent 1edccd0f30
commit f008d1571d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=269109
3 changed files with 18 additions and 2 deletions
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8
sys/amd64/include/vmm.h
View file

@ -270,6 +270,14 @@ vcpu_is_running(struct vm *vm, int vcpu, int *hostcpu)
return (vcpu_get_state(vm, vcpu, hostcpu) == VCPU_RUNNING);
}
#ifdef _SYS_PROC_H_
static int __inline
vcpu_should_yield(struct vm *vm, int vcpu)
{
return (curthread->td_flags & (TDF_ASTPENDING | TDF_NEEDRESCHED));
}
#endif
void *vcpu_stats(struct vm *vm, int vcpu);
void vcpu_notify_event(struct vm *vm, int vcpuid, bool lapic_intr);
struct vmspace *vm_get_vmspace(struct vm *vm);

2
sys/amd64/vmm/intel/vmx.c
View file

@ -2559,7 +2559,7 @@ vmx_run(void *arg, int vcpu, register_t startrip, pmap_t pmap,
break;
}
if (curthread->td_flags & (TDF_ASTPENDING | TDF_NEEDRESCHED)) {
if (vcpu_should_yield(vm, vcpu)) {
enable_intr();
vm_exit_astpending(vmx->vm, vcpu, vmcs_guest_rip());
vmx_astpending_trace(vmx, vcpu, vmexit->rip);

10
sys/amd64/vmm/vmm.c
View file

@ -1105,6 +1105,10 @@ vm_handle_hlt(struct vm *vm, int vcpuid, bool intr_disabled, bool *retu)
}
}
/* Don't go to sleep if the vcpu thread needs to yield */
if (vcpu_should_yield(vm, vcpuid))
break;
/*
* Some Linux guests implement "halt" by having all vcpus
* execute HLT with interrupts disabled. 'halted_cpus' keeps
@ -1128,7 +1132,11 @@ vm_handle_hlt(struct vm *vm, int vcpuid, bool intr_disabled, bool *retu)
t = ticks;
vcpu_require_state_locked(vcpu, VCPU_SLEEPING);
msleep_spin(vcpu, &vcpu->mtx, wmesg, 0);
/*
* XXX msleep_spin() cannot be interrupted by signals so
* wake up periodically to check pending signals.
*/
msleep_spin(vcpu, &vcpu->mtx, wmesg, hz);
vcpu_require_state_locked(vcpu, VCPU_FROZEN);
vmm_stat_incr(vm, vcpuid, VCPU_IDLE_TICKS, ticks - t);
}